Numerous studies have established that a variety of endogenous neuroactive agents including the catecholamines and several neuropeptides are sulfated in vivo and that this reaction may play an essential role in regulating the physiological activity of these substances. There are a number of substrate specific sulfotransferases that are responsible for conjugation of these endogenous biologically active substances and as previously shown, these enzymes differ in their biochemical properties as well as their cellular and subcellular location. It is presently unclear as to contribution that each of the different forms of sulfotransferase play in this process. As previously demonstrated, the soluble sulfotransferase (M and P-PST) in human brain are biochemically distinct from that isolated from common laboratory animals thus, making it essential to characterize these sulfotransferases from human tissues. In this regard, the enzyme, tyrosylprotein sulfotransferase, which is responsible for the post- translational modification of neuropeptides such as cholecystokinin has not been characterized in human tissues including brain. Because of lack of information concerning these important regulatory enzymes the following specific studies are proposed: 1. Completion of our studies on the purification and preparation of antibodies for the different forms of human phenol sulfotransferase and on the immunohistochemical localization of these enzymes. 2. Isolate, purify and characterize the biochemical properties of human brain tyrosylprotein sulfotransferase (TPST) and prepare antibodies to this enzyme for immunohistochemical localization of the enzyme in human brain and other tissues. 3. Clone the genes for the different forms of human soluble (M and P-PST) and membrane-bound sulfotransferase (TPST).